TWI529975B - Wavelength conversion illuminating device - Google Patents

Description

Wavelength conversion illuminating device

The present invention relates to a wavelength conversion semiconductor light emitting device.

Semiconductor light-emitting devices including light-emitting diodes (LEDs), resonant cavity light-emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge-emitting lasers are among the most efficient light sources currently available. Current material systems that have received much attention in the manufacture of high-intensity illumination devices capable of operating across the visible spectrum include Group III-V semiconductors, specifically binary, ternary, and tetragens of gallium, aluminum, indium, and nitrogen. A metaalloy, which is also referred to as a Group III nitride material. Typically, different compositions are epitaxially grown on sapphire, tantalum carbide, Group III nitride or other suitable substrate by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE) or other epitaxial techniques. The semiconductor layer of the dopant concentration is stacked to form a group III nitride light-emitting device. The stack generally includes: one or more n-type layers formed on the substrate doped with, for example, Si; one or more light-emitting layers in an active region formed on the n-type layer; One or more p-type layers formed on the active region doped with, for example, Mg. Electrical contacts are formed on the n-type and p-type regions.

Figure 1 illustrates an LED as described in more detail in US 7,341,878. A semiconductor structure 130 including a light emitting region is attached to the ceramic phosphor 52 by an interface 56. Contacts 18 and 20 are formed on semiconductor structure 130, which are connected to package component 132 by metal interface 134. In some embodiments, all of the layers disposed between package component 132 and ceramic phosphor 52 have a thickness of less than 100 microns. Although FIG. 1 illustrates semiconductor structure 130 mounted on package component 132 in a flip chip configuration in which both contacts 18 and 20 are formed on the same side of the semiconductor structure, in an alternate embodiment, the ceramic phosphor can be removed. One portion of 52 is such that a contact 18 is formed on the side of the semiconductor structure 130 opposite the contact 20.

US 7,341,878 teaches that any luminescent material having the desired properties of the phosphor, such as the high absorption and high quantum efficiency of the light emitted by the primary luminescent layer, can be used to effectively produce light in the embodiments described above. An alternative to a phosphor using a wavelength conversion material having a large imaginary component of the refractive index k at a wavelength emitted by the luminescent region and having a negligible k at the converted wavelength, such as some Group III-V semiconductors and Group II - VI semiconductors. In particular, in a suitable material, k is greater than 0.01, more preferably greater than 0.1, and even more preferably greater than 1, at the wavelength emitted by the primary luminescent region. Means for extracting light from the self-luminous material, such as texturing, roughening or shaping, may be provided.

It is an object of the present invention to provide a wavelength converted semiconductor light emitting device that emits light efficiently.

Embodiments of the invention include a semiconductor light emitting device capable of emitting a first light having a first peak wavelength, and a semiconductor wavelength converting element capable of absorbing the first light and emitting a second light having a second peak wavelength. The semiconductor wavelength conversion element is attached to a support and disposed in a path of light emitted by the semiconductor light emitting device. The semiconductor wavelength conversion element is patterned to include at least a second region having a semiconductor wavelength converting material and at least a second region of the semiconductor-free wavelength converting material disposed between the at least two first regions.

Embodiments of the invention include a semiconductor light emitting device capable of emitting a first light having a first peak wavelength, and a semiconductor wavelength converting element capable of absorbing the first light and emitting a second light having a second peak wavelength. The semiconductor wavelength conversion element is disposed in a path of light emitted by the semiconductor light emitting device and patterned to include at least two first regions having a semiconductor wavelength converting material and disposed in the at least two first regions There is at least a second region between the semiconductor-free wavelength converting materials. A wavelength converting component is disposed in the at least one second region, the wavelength converting component capable of absorbing the first light and emitting a third light having a third peak wavelength.

Embodiments of the invention include a first illumination device capable of emitting a first light having a first peak wavelength, and a second illumination device capable of emitting a second light having a second peak wavelength. The second light emitting device includes a semiconductor light emitting device capable of emitting a third light having a third peak wavelength, and a semiconductor wavelength converting element capable of absorbing the third light and emitting the second light.

A semiconductor wavelength conversion element provides efficient and spectrally narrow wavelength conversion for excellent color rendering and high illumination output.

In an embodiment of the invention, the semiconductor wavelength conversion component is combined with a semiconductor light emitting device. Although in the following examples, the semiconductor light emitting device is a Group III nitride LED that emits blue or UV light, semiconductor light emitting devices other than LEDs, such as laser diodes and other material systems (such as other III) may be used. A semiconductor light-emitting device comprising a Group-V material, a Group III phosphide, a Group III arsenide, a Group II-VI material, or a Si-based material.

Any suitable LED can be used. 2 and 3 illustrate two examples of suitable LEDs 10. In order to produce the apparatus illustrated in Figures 2 and 3, the semiconductor structure 22 is grown on a growth substrate. The semiconductor structure 22 includes a light emitting or active region sandwiched between an n-type region and a p-type region. The n-type region may be grown first and may include a plurality of layers having different compositions and dopant concentrations, including, for example, a preparation layer such as a buffer layer or a nucleation layer, which may be n-type Or not intentionally doped, and may be an n-type or even p-type device layer that is designed to achieve the specific optical or electrical properties required for the luminescent region to effectively illuminate. The luminescent or active region is grown on the n-type region. Examples of suitable illuminating regions include a thick or thin single luminescent layer, or a plurality of quantum well illuminating regions comprising a thin or thick plurality of luminescent layers separated by a barrier layer. The P-type region can then be grown on the luminescent region. Similar to the n-type region, the p-type region can include multiple layers having different compositions, thicknesses, and dopant concentrations, including layers that are not intentionally doped or n-type layers.

As illustrated in Figure 2, a P-junction metal 26 is placed over the p-type region, and then the p-type region and portions of the active region are etched away to expose the n-type layer for metallization. The p-contact 26 and the n-contact of this embodiment are on the same side of the device. As illustrated in Figure 2, the p-contact 26 can be disposed between a plurality of n-contact regions 24, although this is not required. In some embodiments, either or both of n-contact 24 and p-contact 26 are reflective, and the device is mounted such that light is directed through the top of the device in the orientation illustrated in FIG. extract. In some embodiments, the contacts may be limited in range or made transparent, and the device may be mounted such that light is extracted via the surface forming the contacts. The semiconductor structure is attached to the mounting station 28. The growth substrate can be removed (as illustrated in Figure 2), or it can be maintained as part of the device. In some embodiments, the semiconductor layer exposed by removing the growth substrate is patterned or roughened, which may improve light extraction from the device.

In the vertical exit LED illustrated in FIG. 3, an n-contact is formed on one side of the semiconductor structure, and a p-contact is formed on the other side of the semiconductor structure. For example, p-contact 26 can be formed on the p-type region and the device can be attached to mounting plate 28 via p-contact 26. All or a portion of the substrate may be removed, and the n-contact 24 may be formed on a surface of one of the n-type regions exposed by removing a portion of the substrate. Electrical contact to the n-contact can be made by wire bonding (as illustrated in Figure 3) or by any other suitable structure.

The semiconductor wavelength conversion element is disposed in the path of the light emitted from the LED 10. The semiconductor wavelength conversion element can be merely a wavelength converting material in the device, or can be combined with other wavelength converting materials such as phosphors, quantum dots, other semiconductor wavelength converting elements or dyes to produce monochromatic light of white or other colors. Other wave converting materials can be, for example, pre-formed ceramic phosphor layers that are glued or bonded to or spaced apart from the LED, or powdered phosphors or quantum dots disposed in an inorganic or organic encapsulant, the encapsulation The agent is applied to the LED by stamping, screen or ink jet printing, spraying, sedimentation, evaporation, sputtering or otherwise. The wavelength converting material absorbs light emitted by the LED and emits light of different wavelengths. All or only a portion of the light emitted by the LEDs can be converted by the wavelength converting material. The unconverted light emitted by the LED can be part of the final spectrum of light, but this need not be the case. The semiconductor wavelength conversion element can efficiently convert the light it absorbs into light of different wavelengths. The light emitted by the semiconductor wavelength conversion element can have a spectral width that is narrower than the spectral width of the light emitted by the conventional phosphor. A narrower spectral width may be advantageous (especially for semiconductor wavelength conversion elements that emit red light) to produce a device that emits white light with good color rendering and high luminous efficiency.

Examples of commonly used combinations include: blue-emitting LEDs combined with wavelength-converting materials that emit yellow light; blue-emitting LEDs combined with wavelength-converting materials that emit green and red light; and emitted UV light combined with wavelength-converting materials that emit blue and yellow light. LED; and LED emitting UV light combined with a wavelength converting material that emits blue, green, and red light. A wavelength converting material that emits light of other colors may be added to trim the spectrum of light emitted by the device. Examples of suitable wavelength converting materials include (Lu, Y, Gd) ₃ (AlGa) ₅ O ₁₂ : CePr, Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ , Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Sr, Ca , Ba)Si _x N _y O _z :Eu ²⁺ (x=1.5-2.5, y=1.5-2.5, z=1.5-2.5), (Ba,Ca,Sr) ₃ Si ₆ O ₁₂ N ₂ :Eu ^{2 +} , (Sr, Ca, Ba) ₂ Si ₅ N ₈ :Eu ²⁺ and SrSi ₂ N ₂ O ₂ :Eu ²⁺ .

FIG. 4 illustrates an embodiment of the invention including LED 10 and semiconductor wavelength conversion element 12. The semiconductor wavelength conversion element 12 is a semiconductor layer of at least one epitaxial growth. Different from the active area of the LED 10 that is electrically twitched (meaning that the active area emits light when the n-contact and the p-contact are forward biased), the semiconductor wavelength conversion element is optically twitched, meaning The semiconductor wavelength conversion element absorbs light of a first wavelength (light from an active region of the LED 10) and, in response, emits a second, longer wavelength light. The semiconductor wavelength conversion element 12 is electrically passive and therefore does not need to be connected to a metal contact. Alternatively, semiconductor wavelength conversion element 12 can be doped such that it is electrically conductive and can be part of the conductive path of the n-contact or p-contact of LED 10.

The semiconductor wavelength conversion element 12 is grown on the LED 10 or grown on a separate growth substrate. In some embodiments, the semiconductor wavelength conversion element 12 is grown on a separate growth substrate, independent of the growth and processing of the LED 10. The semiconductor wavelength conversion element 12 can be bonded to the LED 10 by an optional bonding layer 11, or can be directly bonded to the LED 10 without an intervening bonding layer. After bonding to the LED 10 or to another structure for mechanical support, the growth substrate of the semiconductor wavelength conversion element 12 can remain as part of the device, or can be melted by any suitable technique (such as etching, grinding, or laser melting). And lift off).

In some embodiments, semiconductor wavelength conversion element 12 is a single luminescent layer. FIG. 5 illustrates a multilayer semiconductor wavelength conversion element 12. In the structure illustrated in FIG. 5, the three light-emitting layers 32 are separated by the barrier layer 34. More or fewer luminescent layers 32 can be used. For example, the luminescent layer 32 and the barrier layer 34 can form a multiple quantum well or superlattice structure. The luminescent layer 32 and the barrier layer 34 are disposed between two optional cover layers or confinement layers 30. The confinement layer 30 can have the same composition, doping and thickness as the barrier layer 34, or can be different. In some embodiments, the light emitting region 33 of the semiconductor wavelength conversion element 12 is a single light emitting layer 32 disposed between the two cap layers 30, for example, as a double heterostructure or a single quantum well heterostructure.

Semiconductor wavelength conversion element 12 can be designed to minimize absorption in non-emissive layers, such as confinement layer 30 and barrier layer 34, to efficiently convert or transfer light from LED 10 with minimal loss, and to convert it. The output of light is the largest. For overall conversion, all of the photons emitted by the LED 10 (eg, UV, blue, green, and/or yellow) and incident on the semiconductor wavelength conversion element 12 can be absorbed to produce converted light (eg, green, yellow) And/or red) photons while minimizing losses and maximizing conversion efficiency.

The confinement layer 30, the barrier layer 34, and the luminescent layer 32 are all capable of absorbing light from the LED 10, but typically only the luminescent layer emits light. Therefore, in some embodiments, it is desirable to maximize the thickness of the luminescent layer relative to the thickness of the non-emissive limiting layer and the barrier layer. The total thickness of the semiconductor wavelength conversion element affects the amount of light from the LED 10 absorbed by the wavelength conversion element via Beer's Law I _transmitted =I _o e ^-αx , where x is the light absorbing material (semiconductor wavelength conversion element) The thickness, and α is the absorption coefficient. If the wavelength conversion element is too thick, the light from the LED 10 will not pass. In some embodiments, the luminescent layer includes defects that act as non-radiative recombination centers. If the luminescent layer is too thick, non-radiative recombination may prevail over radiation recombination, making the efficiency of the semiconductor wavelength conversion element undesirably low. Additionally, in some embodiments, the confinement layer has a surface that acts as a reservoir for carrier recombination. If the confinement layer is too thin, the carriers may escape from the luminescent layer and diffuse to the surface of the confinement layer (at which the carriers are recombined in a non-radiative manner), thereby reducing the semiconductor wavelength conversion element. effectiveness.

Surface passivation of the semiconductor wavelength conversion element reduces the density of surface states and reduces surface recombination. Surface passivation is especially important for confinement layers containing high Al, which may have a high surface recombination rate (e.g., about 10 ⁶ cm/s for In _0.5 Al _0.5 P). Surface passivation of the semiconductor wavelength conversion element can passivate defects of dangling bonds and semiconductor surfaces and can reduce surface recombination. Examples of suitable surface passivation materials and techniques include sulfur coated by, for example, (NH ₄ ) ₂ S _x treatment, hydrogen passivation, oxygen passivation, nitrogen passivation, and natural oxide formation.

In some embodiments, at least one non-emissive layer of semiconductor wavelength conversion element 12, such as confinement layer 30 or barrier layer 34, for example, is an aluminum-containing Group III phosphide or Group III arsenic such as AlInGaP, AlInGaAs, or AlInP. Material. The Al content of the AlInGaP or AlInP layer can be high (for example, Al 50%). Barrier layer 34 and/or cap layer 30 may be an AlInGaP or AlInP layer that is not intentionally doped or slightly n-doped (eg, a dopant concentration of less than 10 ¹⁸ cm ^-3 ). These barrier layers 34 and cover layer 30 are preferably thin, for example, less than 2000 in some embodiments. Thick, and in some embodiments less than 1000 . In some embodiments, the confinement layer 30 closest to the LED 10 is less than 1000 thick. The confinement layer 30 opposite the LED 10 can be relatively thick and can be, for example, 1 μm thick or thicker. In some embodiments, luminescent layer 32 is (Al _x Ga _1-x ) _0.5 In _0.5 P that is lattice matched to GaAs. The luminescent layers cover the wavelength range from green to red (about 5300) Or 2.33 eV (for x=1) to 6600 Or 1.89 eV (for x=0)). For example, GaP having a 4% lattice mismatch with GaAs can be used as the confinement layer 30, the barrier layer 34, or the luminescent layer 32. The total thickness of all of the luminescent layers in the semiconductor wavelength conversion element is between 10 nm and 3 μm in some embodiments, between 20 nm and 1 μm in some embodiments, and at least 10 in some embodiments. Nm and in some embodiments is between 50 nm and 100 nm.

In some embodiments, at least one of the light-emitting layers 32 of the semiconductor wavelength conversion element 12 is a Group II-VI compound semiconductor (such as CdMgZnSe that is tightly lattice-matched to InP), which covers from blue to red (4600) To 6300 ) The wavelength range. An example of a suitable luminescent layer 32 is described in US 2007/0284565, which is incorporated herein by reference. In Group II-VI embodiments, the composition is tuned to be transparent to the pump wavelength (eg, Cd _0.24 Mg _0.43 Zn _0.33 Se has 2.9 eV or 4280 The band gap), the confinement layer 30 can be thicker. For example, the barrier 34 can be precisely tuned to absorb the pump (eg, Cd _0.35 Mg _0.27 Zn _0.38 Se has 2.6 eV or 4800 Band gap). The or the luminescent layer 32 can be precisely tuned for the desired converted wavelength, for example, at 2.3 eV or 5400 Cd _0.33 Zn _0.67 Se emitted in green light to Cd _0.70 Zn _0.30 Se emitted in red light at 1.9 eV or 655 nm. As with the Group III-V embodiments described above, Group II-VI wavelength converters can have luminescence of, for example, multiple quantum well structures, superlattices, single layers, double heterostructures, or single quantum well heterostructures. region.

In some embodiments, semiconductor wavelength conversion element 12 includes a support 35 to add thickness and mechanical robustness to the structure. For example, any relatively transparent, translucent, scattering or wavelength converting material can be used, such as sapphire, glass, SiC, ScAlMgO, ZnS, ZnSe, GaP, ceramic, ceramic phosphor, phosphor or scattering material in glass, Or polymer. In such embodiments, the total thickness of the semiconductor wavelength conversion element can be 20 μm or greater. In other embodiments, the semiconductor wavelength conversion element 12 has a total thickness of 5 μm or less. In some embodiments, semiconductor wavelength conversion element 12 includes a support 35 that includes a ceramic phosphor. In some embodiments, the support 35 is an optical element such as a lens. For example, the support 35 can be a hemispherical lens or a Fresnel lens. In some embodiments (eg, if the support 35 is a lens), the diameter of the support 35 can be greater than the length of the edge or diagonal of the LED 10.

The semiconductor wavelength conversion element 12 can be a self-contained structure that is attached to, for example, the LED 10, the support 35, or another layer or material such as a ceramic phosphor. The semiconductor wavelength converting element material can also be decomposed, broken, powdered or ground and added to a bonding agent such as polyoxyxide, sol gel or a bonding material or layer such as listed below. The semiconductor wavelength conversion element 12 can be a quantum dot or a nanoparticle.

The bonding layer 11 may be any suitable material such as: lead chloride; lead bromide; potassium fluoride; zinc fluoride; aluminum, lanthanum, cerium, boron, lead, lithium, phosphorus, potassium, cesium, sodium, cesium, cesium , an oxide of tungsten or zinc; or any mixture of the foregoing. The bonding layer 11 may also include: Group III-V semiconductors including, but not limited to, gallium arsenide, gallium nitride, gallium phosphide, and indium gallium phosphide; Group II-VI semiconductors including, but not limited to, cadmium selenide, Cadmium sulfide, cadmium telluride, zinc sulfide, zinc selenide and zinc telluride; Group IV semiconductors and compounds, including but not limited to germanium, antimony and antimony carbide; organic semiconductors, oxides, metal oxides and rare earth oxides, including But not limited to aluminum, antimony, arsenic, antimony, boron, cadmium, antimony, chromium, cobalt, copper, gallium, germanium, indium, indium tin, lead, lithium, molybdenum, antimony, nickel, antimony, phosphorus, potassium, antimony, Oxides of sodium, strontium, barium, titanium, tungsten, zinc or zirconium; oxyhalides such as bismuth oxyfluoride; fluorides, chlorides and bromides including, but not limited to, calcium, lead, magnesium, potassium, sodium and Fluoride, chloride and bromide of zinc; metals including, but not limited to, indium, magnesium, tin and zinc; yttrium aluminum garnet (YAG), phosphide compounds, arsenide compounds, telluride compounds, nitride compounds, high a refractive index organic compound; and a mixture or alloy of the above. The refractive index of the bonding layer 11 may be greater than 1.5 in some embodiments, greater than 1.6 in some embodiments, greater than 1.7 in some embodiments, greater than 1.8 in some embodiments, greater than 1.9 in some embodiments, in some implementations In an example greater than 2.0, in some embodiments greater than 2.1 or in some embodiments greater than 2.2.

The bonding layer 11 may be substantially free of conventional organic-based adhesives such as epoxy resins because such adhesives tend to have a low refractive index. The bonding layer 11 can also be formed of a material having a low refractive index, that is, a material having a refractive index of less than about 1.5 at the emission wavelength of the LED die. For example, magnesium fluoride is one such bonding material. The low refractive index optical glass, epoxy resin and tantalum may also be suitable low refractive index bonding materials.

The bonding layer 11 may also be formed of a glass bonding material such as Schott glass LaSFN35, LaF10, NZK7, NLAF21, LaSFN18, SF59 or LaSF3, or Ohara glass SLAH51 or SLAM60, or a mixture of the above. The bonding layer 11 may also be formed of a high refractive index glass such as, for example, (Ge, As, Sb, Ga) (S, Se, Te, F, Cl, I, Br) chalcogenide or chalcogenide halide glass. Low refractive index materials such as glass and polymers can be used. Both a high refractive index resin and a low refractive index resin such as polyfluorene oxide or decane are commercially available from manufacturers such as Shin-Etsu Chemical Co., Ltd. (Tokyo, Japan). The side chain of the siloxane backbone can be modified to change the refractive index of the poly argon.

The bonding layer 11 can be applied by any suitable method, including evaporation, sputtering, chemical vapor deposition, dispensing, printing, spraying, spin coating or knife coating. The high refractive index bonding material may be deposited in the form of a fluid and may remain fluid until the moment of attachment, or may be partially cured or gelled at the point of attachment, or may be a solid that is tackified upon heating to enable easy attachment. The high refractive index bonding material can react to form a cured bond that can range from a gelled state to a hard resin.

In some embodiments, an optional second wavelength conversion element 14 is disposed on the semiconductor wavelength conversion element 12. The optional second wavelength conversion element 14 can be any of the wavelength conversion materials described above. The optional bonding layer 15 can attach the second wavelength converting element 14 to the semiconductor wavelength converting element 12, or the second wavelength converting element 14 and the semiconductor wavelength converting element 12 can be directly bonded without an intervening bonding layer, or a second The wavelength converting element 14 and the semiconductor wavelength converting element 12 may be spaced apart from each other. The bonding layer 15 can be formed of the materials and by the method described above for the bonding layer 11. The bonding layer 15 does not have to be the same material as the bonding layer 11. In some embodiments, the semiconductor wavelength conversion element 12 is opposite in position to the second wavelength conversion element 14 such that the second wavelength conversion element 14 is disposed between the LED 10 and the semiconductor wavelength conversion element 12.

In some embodiments, LED 10 emits blue light, semiconductor wavelength conversion element 12 absorbs blue light and emits red light, and second wavelength conversion element 14 is a ceramic phosphor plate that absorbs blue light and emits yellow or green light. In some embodiments, the light exit surface (typically the top surface) of the top wavelength conversion element (the second wavelength conversion element 14 in the configuration illustrated in Figure 4) is roughened or patterned to, for example, by Etching (with or without additional photolithography or embossing steps) enhances light extraction.

In some embodiments, an optional light extraction element 16 is disposed on the top wavelength conversion element. Examples of light extraction element 16 include a block or plate having a roughened or patterned top and/or bottom surface, or an optical element such as a lens. In some embodiments, light extraction element 16 has a refractive index that closely matches second wavelength conversion element 14, semiconductor wavelength conversion element 12, or LED 10. The optional bonding layer 17 can attach the light extraction element 16 to the top wavelength conversion element, or the light extraction element 16 and the top wavelength conversion element can be directly bonded without the intervening bonding layer, or the light extraction element 16 and the top wavelength conversion The components can be spaced apart from one another. The bonding layer 17 can be formed of the materials and by the method described above for the bonding layer 11. The bonding layer 17 does not have to be the same material as the bonding layers 11 and/or 15. In some embodiments, the refractive index of bonding layer 17 is closely matched to second wavelength converting element 14 or LED 10. The refractive index of light extraction element 16 and bonding layer 17, bonding layer 11 or bonding layer 15 may be greater than 1.5 in some embodiments, greater than 1.6 in some embodiments, greater than 1.7 in some embodiments, and greater than in some embodiments in some embodiments. 1.8, in some embodiments greater than 1.9, in some embodiments greater than 2.0, in some embodiments greater than 2.1, or in some embodiments greater than 2.2. The refractive index of light extraction element 16 and bonding layer 17 may be equal to or less than 2.4 in some embodiments or equal to or less than 3.5 in some embodiments. In some embodiments, light extraction element 16 can be larger than LED 10 and can extend beyond the edge of LED 10. For example, if the light extraction element 16 is a lens, the diameter of the lens can be greater than the length of the edge or diagonal of the LED 10.

In some embodiments, the LED 10, semiconductor is roughened, textured, or patterned, for example, by mechanical polishing, dry etching, photoelectrochemical etching, molding, grinding, processing, stamping, hot stamping, or chemical polishing. A top surface of one, some or all of the wavelength conversion element 12 and the second wavelength conversion element 14.

In some embodiments, one or more of the bonding layers 11, 15 and 17 include a luminescent material that converts light of a wavelength emitted by the active area of the LED 10 to other wavelengths. The luminescent material may be a conventional phosphor particle, an organic semiconductor, a Group II-VI semiconductor or a Group III-V semiconductor, a Group II-VI semiconductor or a Group III-V semiconductor quantum dot or nanocrystal, Dyes, polymers, or materials such as GaN. If the bonding layer comprises conventional phosphor particles, the bonding layer should be thick enough to accommodate particles typically having a size of from about 5 microns to about 50 microns.

In some embodiments, as illustrated in Figures 7, 8, and 9, semiconductor wavelength conversion element 12 is patterned. For example, semiconductor wavelength conversion element 12 can be patterned to include at least two first regions having semiconductor wavelength converting materials and at least a second region of semiconductor-free wavelength converting material disposed between the first regions.

In the apparatus illustrated in Figure 7, the semiconductor wavelength conversion element 12 is patterned to form a region 46 having a wavelength converting material and a region 48 having no wavelength converting material. The semiconductor wavelength conversion element 12 can be selectively formed only in a particular region by, for example, stamping or screen printing or inkjet printing, or formed as a removed region 48 by, for example, conventional lithography techniques. A continuous sheet of material. The wavelength converted light is emitted by region 46 and the unconverted light from LED 10 is emitted in region 48. In one example of the apparatus illustrated in Figure 7, LED 10 emits blue light and region 46 emits yellow light such that the combined light appears white. In another example of the apparatus illustrated in Figure 7, LED 10 emits blue light, region 46 emits yellow or green light, and the apparatus is combined with a wavelength converting component that emits red light spaced apart from the apparatus of Figure 7. In another example of the apparatus illustrated in Figure 7, LED 10 emits blue light, region 46 emits red light, and the apparatus is combined with a wavelength conversion component that emits yellow light or emits green light spaced apart from the apparatus of Figure 7. . Adding red light to blue and yellow or green light provides a milder white light and provides better color rendering than a device without red light.

In the device illustrated in Figure 8, the patterned semiconductor wavelength conversion element 12 is formed on an optional support member 51. The patterned semiconductor wavelength conversion element 12 includes a region 46 having a wavelength converting material and a region 50 having other materials. In some embodiments, region 50 is a transparent, translucent or scattering material (such as polyfluorene) that is filled in the gap between regions 46. In some embodiments, region 50 is another wavelength converting material that emits light of a different color. Region 50 is another semiconductor wavelength converting material, or another wavelength converting material such as a phosphor. For example, region 46 can emit yellow or green light, and region 50 can emit red light, or region 46 can emit red light, and region 50 can emit yellow or green light. The support member can be, for example, another wavelength converting element such as a ceramic phosphor, or a non-wavelength converting support member as described above. In an example of the apparatus illustrated in Figure 8, the support member 51 is a ceramic phosphor that emits yellow or green light, and the region 46 is a semiconductor wavelength conversion element that emits red light. In this example, region 50 is a transparent material or is omitted, leaving a gap between regions 46. For example, the blue light emitted by the LED 10 can be combined with the yellow or green light emitted by the ceramic phosphor 51 and the red light emitted by the semiconductor wavelength conversion element 12 to form white light. In another example, the blue light emitted by the LED 10 can be combined with the yellow or green light emitted by the semiconductor wavelength conversion element 12 and the red light emitted by the ceramic phosphor 51 to form white light. In another example, the UV light emitted by the LED 10 can be combined with the blue light emitted by the ceramic phosphor 51 and the yellow or green light emitted by the semiconductor wavelength conversion element 12 to form white light. The support 51 can be between the LED 10 and the patterned semiconductor wavelength conversion element 12 (as shown in FIG. 8) or it can be opposite the LED 10, wherein the patterned semiconductor wavelength conversion element 12 is interposed.

In the apparatus illustrated in FIG. 9, the patterned semiconductor wavelength conversion element 12 includes three distinct regions 50, 52, and 54. In some embodiments, all three regions 50, 52, and 54 are different wavelength converting materials, at least one of which is a semiconductor. In some embodiments, two of regions 50, 52, and 54 are different wavelength conversion elements, and a third of regions 50, 52, and 54 are non-wavelength-transparent transparent or translucent materials, or in regions 50, 52. There is no material gap between the two and 54. In some embodiments, only two types of regions having two different wavelength converting materials are included, and the third type of regions are omitted. In one example of the apparatus illustrated in Figure 9, LED 10 emits blue light, one of regions 52, 54 is a semiconductor wavelength converting material, region 52 is a red emitting semiconductor material or phosphor, and region 54 is an emitting yellow. Light or green semiconductor material or phosphor, and region 50 is omitted. In another example of the apparatus illustrated in Figure 9, LED 10 emits blue light, one of regions 52, 54 is a semiconductor wavelength converting material, region 52 is a red light emitting semiconductor material or phosphor, and region 54 is an emission. A yellow or green semiconductor material or phosphor, and region 50 is a transparent material or a gap that allows blue light from LED 10 to escape unconverted.

The patterned semiconductor wavelength conversion elements illustrated in Figures 7, 8 and 9 can be combined with any of the other features of the invention described herein. The patterned semiconductor wavelength conversion elements illustrated in Figures 7, 8 and 9 can be spaced apart from the LEDs 10 and not disposed on the LEDs 10 as illustrated.

Figure 6 illustrates a light source for producing white light. The device 41 for generating red light is combined with the device 42 for generating green light and the device 43 for generating blue light. Any or all of the devices 41, 42 and 43 may be any of the devices described above or may include some or all of the features described above. The means 42 and 43 for generating green and blue light may be, for example, a group III nitride light emitting diode. Light from such diodes may or may not be wavelength converted. For example, the device 42 that produces green light can be an LED that emits blue or UV light in combination with a wavelength converting element that emits green light. The device 41 that produces red light includes an LED in combination with a semiconductor wavelength conversion element that emits red light and can be as described above with reference to Figures 4 and 5. The LED can emit green, blue or UV light. The semiconductor wavelength conversion element is configured such that sufficient light emitted by the LED is converted such that light from device 41 appears red. In some embodiments, all of the devices 41, 42 and 43 are flip chip.

In some of the embodiments of Figure 6, device 43 is omitted. For example, device 41 can emit blue light in combination with yellow or green light emitted by device 42. Device 42 can be a blue emitting LED in combination with a phosphor that emits yellow or green light, a ceramic phosphor, or a semiconductor wavelength conversion element. The blue light from the LED may be present in the spectrum of the light emitted by device 42 or may not be present in the spectrum of the light emitted by device 42. In another example, the blue emitting device 41 and the yellow or green emitting device 42 are combined with a red emitting phosphor, ceramic phosphor or semiconductor wavelength converting element to produce a white light source. In another example, a device 41 that emits yellow or green light is combined with a device 42 that emits red and blue light to produce a white light source. The device 41 for emitting yellow or green light may be an LED that directly generates yellow or green light by a group III nitride or a group III phosphide light emitting layer, or may be a phosphor that emits yellow or green light or ceramic phosphorescence. A blue light emitting LED combined with a bulk or semiconductor wavelength converting element. The means 42 for emitting red and blue light may be a blue-emitting LED combined with a red-emitting phosphor, a ceramic phosphor or a semiconductor wavelength conversion element. In another example, the red light emitting device 41 is combined with a device 42 that emits yellow or green and blue light to produce a white light source. The red light emitting device 41 may be an LED that directly generates red light, or may be a blue light emitting LED combined with a red light emitting phosphor, a ceramic phosphor, or a semiconductor wavelength converting element. The means 42 for emitting yellow or green light and blue light may be a blue light emitting LED combined with a phosphor emitting yellow or green light, a ceramic phosphor or a semiconductor wavelength converting element.

The combination of a semiconductor wavelength conversion element that emits red light and an LED that emits blue, green, or yellow light can be used to produce spectrally narrow red light that is difficult to produce by conventional phosphors. The spectrally narrow red light source can be used for white light sources that are efficient and have good color rendering. Figure 10 shows the spectra of a red phosphor and a semiconductor wavelength converting element. The thick line on Figure 10 is the emission spectrum of a red photonitride silicate phosphor having a full width at half maximum (FWHM) of about 100 nm. The thin line on Figure 10 is the emission spectrum of a red-emitting semiconductor wavelength conversion element having a FWHM of about 25 nm or less.

The combination of the semiconductor wavelength conversion element and the semiconductor light emitting device described herein effectively emits red light having a desired narrow spectral width that is not achievable with current phosphors. Due to the limitations of phosphors in producing red light, conventional white light sources typically combine devices having different material systems, such as a combination of III-nitride devices for producing blue and green light and III for generating red light. Family phosphide or group III arsenide device. Devices with different material systems can have different operating characteristics and configurations, such as depending on current (drop) or temperature (heat/cold factor), forward voltage, forward or reverse current capability, heat dissipation and temperature handling capabilities. effectiveness. In addition, complications may arise due to the mixing of devices having different sized footprints, different sized wafers, and different geometries, such as flip-chip vertical wafers. In contrast, in embodiments of the invention, a white light source can be formed from only a group III nitride device. The spectrally narrow red light can be generated by a III-nitride device combined with a semiconductor wavelength conversion element. The light source can be formed to have optimal color, efficiency, and operational characteristics.

Having described the invention in detail, it is to be understood by those skilled in the art that the present invention may be modified without departing from the spirit of the invention as described herein. Therefore, the scope of the invention is not intended to be limited to the specific embodiments illustrated and described.

10. . . LED (light emitting diode)

11. . . Bonding layer

12. . . Semiconductor wavelength conversion element

14. . . Second wavelength conversion element

15. . . Bonding layer

16. . . Light extraction element

17. . . Bonding layer

18. . . contact

20. . . contact

twenty two. . . Semiconductor structure

twenty four. . . n contact / n contact area

26. . . P contact metal / p contact

28. . . Mounting table

30. . . Overlay or confinement layer

32. . . Luminous layer

33. . . Luminous area

34. . . Barrier layer/barrier

35. . . supporting item

41. . . Device

42. . . Device

43. . . Device

46. . . Area with wavelength converting material

48. . . Area without wavelength conversion material

50. . . Area with other materials

51. . . Support member / ceramic phosphor / support

52. . . Ceramic phosphor/region

54. . . region

56. . . interface

130. . . Semiconductor structure

132. . . Package component

134. . . Metal interface

Figure 1 illustrates a prior art device including a ceramic phosphor layer attached to an LED.

Figure 2 illustrates a thin film flip chip semiconductor light emitting device.

Figure 3 illustrates a vertical semiconductor light emitting device.

4 illustrates an LED in combination with a semiconductor wavelength conversion element, an optional second wavelength conversion element, and an optional light extraction element.

Figure 5 illustrates an example of a semiconductor wavelength conversion element.

Figure 6 illustrates a light source for producing white light.

Figure 7 illustrates an apparatus having a patterned semiconductor wavelength conversion element.

Figure 8 illustrates an apparatus having patterned semiconductor wavelength conversion elements formed on a support member.

Figure 9 illustrates an apparatus having a plurality of wavelength converting elements formed in a pattern.

Figure 10 illustrates the emission spectra of the phosphor and the semiconductor wavelength conversion element.

10. . . LED (light emitting diode)

11. . . Bonding layer

12. . . Semiconductor wavelength conversion element

14. . . Second wavelength conversion element

15. . . Bonding layer

16. . . Light extraction element

17. . . Bonding layer

Claims (18)

A light emitting structure comprising: a semiconductor light emitting device capable of emitting first light having a first peak wavelength; and a semiconductor wavelength converting element capable of absorbing the first light and having a first emission a second light having a second peak wavelength; wherein: the semiconductor wavelength conversion element is attached to a support member and disposed in a path of light emitted by the semiconductor light emitting device; the support member is capable of emitting one a ceramic phosphor of a third light of a third peak wavelength; and the semiconductor wavelength conversion element is patterned to include a first region of the at least two semiconductor wavelength converting materials and disposed in the at least two first regions At least a second region of the semiconductor-free wavelength converting material. The structure of claim 1, wherein the second peak wavelength is red light. The structure of claim 1, wherein the semiconductor wavelength conversion element comprises at least one light emitting layer, wherein the at least one light emitting layer is one of a group III-V semiconductor and a group II-VI semiconductor. The structure of claim 1, wherein one of the surfaces of the ceramic phosphor is textured and roughened. The structure of claim 1, wherein the third peak wavelength is one of green light and yellow light. The structure of claim 1, wherein the support is one of transparent, translucent, and scattering. The structure of claim 1, wherein the support member is a lens. The structure of claim 7, wherein the lens is one of a semispherical lens and a Fresnel lens. The structure of claim 7, wherein one of the lenses has a diameter greater than a diagonal of the semiconductor light emitting device. The structure of claim 1, further comprising a light extraction element, wherein the semiconductor wavelength conversion element is disposed between the semiconductor light emitting device and the light extraction element. The structure of claim 10, wherein the light extraction element comprises a transparent plate having a roughened or patterned surface. The structure of claim 1, wherein the semiconductor wavelength conversion element comprises at least one luminescent layer disposed between the first confinement layer and the second confinement layer. The structure of claim 12, wherein the semiconductor wavelength conversion element further comprises: an additional luminescent layer disposed between the first confinement layer and the second confinement layer; and disposed on the at least one luminescent layer and the additional luminescent layer A barrier between the layers. The structure of claim 1, further comprising at least one bonding layer, wherein the at least one bonding layer is disposed at an interface between the semiconductor light emitting device and the semiconductor wavelength conversion element and at the semiconductor wavelength conversion element and the support One of the interfaces between the pieces. The structure of claim 14, wherein the bonding layer is an oxide. The structure of claim 1, wherein one of the surfaces of the semiconductor wavelength conversion element is textured and roughened. The structure of claim 1, wherein one of the surfaces of the semiconductor wavelength conversion element is passivated. The structure of claim 1, further comprising one of the wavelength conversion elements disposed in the at least one second region.